Conventionally, there is known a laser processing apparatus for irradiating a machining surface of a workpiece by a laser beam output from a laser beam source, constantly monitoring the laser beam reflected by the machining surface by a reflected light monitoring unit, and issuing an alarm if a detection value of the reflected light monitoring unit is smaller than a predetermined value (for example, see PTL 1).
Also, there is known a laser processing system including a laser processing apparatus including a laser nozzle for radiating a laser beam downward, a light receiving body that is arranged below the laser nozzle, a first handle for moving the light receiving body in an X-axis direction, which is a horizontal direction, a second handle for moving the light receiving body in a Y-axis direction, which is a horizontal direction, a laser beam receiving unit that is attached to the light receiving body and that is capable of measuring an output from the laser nozzle, and a cover for covering the light receiving body so as to cover the laser beam receiving unit, and a manipulator (for example, see PTL 2).
According to this laser processing system, at the time of measuring an output from the laser nozzle, the cover of the light receiving body is removed by the manipulator, and the first and the second handles are operated by the manipulator and the laser beam receiving unit is moved to a position for measuring output from the laser nozzle, to thereby perform accurate output measurement.